Composite plastics board for making box file - has corrugated central layer covered by smooth outer layers of plastics and has perforated lines to form box spine

摘要

The box file is made from composite boards of plastics. The composite sheet consists of a central layer (11) of corrugated plastics which is covered by outer layers (9, 10) of smooth plastics sheet. The composite sheet is folded along lines of perforations (5) in the corrugated layer to form the two covers (2, 4) and the spine (3) of the box file (1). The outer edges (8) of the covering sheets (9, 10) are welded together. The document retaining rods (14, 15) are attached to a plate (12) fixed to the back (4) of the file. A special slot (17) cut in the front cover (2) fits over the curved end (13) of the rods(15) and obviates the need for any additional retaining device.